1. Field of the Invention
The present invention relates to an image processor to take in and process image data. More specifically the present invention relates to an image processor to extract only an image of a specific object in a designated space among input images.
2. Description of the Related Art
Various image processing technologies to extract only a specific object among an image have been proposed by those skilled in the art.
A technology according to the prior art is the technology disclosed in the Japanese Patent Publication (Kokai) No. Heisei 7-177423 "A Compound Eye Image Pickup Device". In the above publication, a method to calculate the distance to an object based on a disparity between images captured by plural image pickup devices is proposed. The compound eye image pickup device described in the above publication is one to takes in plural image signals by using plural image pickup systems in order to pick up an image of an object and creates a synthetic image, and is equipped with a means to control the order for the corresponding point extracting portion that extracts positions of the common portions from plural images to be obtained by each of the image pickup systems to judge the common portions in an image. Thereby, in the case to obtain a synthetic panoramic image from plural images, identical objects existing in each image is extracted in a rapid manner. The object extracting method described in the above publication finds out corresponding portions in each image taken by the plural image pickup devices, and extracts a coordinate difference in the image as a disparity, and separates objects existing in the foreground of the image by using the size of extracted disparity.
However, in the conventional method to judge the depth by disparity by using the plural image pickup devices, a threshold value to distinguish the foreground and the background greatly affects the accuracy of extraction, and difficulty to determine such a threshold value prevents accurate extraction, which has been a problem with the conventional method according to the prior art.
The device in the above Japanese Patent Publication (Kokai) No. Heisei 7-177423 tries to solve the difficulty in determining the above threshold value by obtaining three dimensional coordinates from disparitys of plural image pickup systems. For that purpose, however a great deal of efforts are required to control and measure the relative position and optical axis angles among plural image pickup devices. And in the case of false corresponding wrong points in the corresponding point acquiring search among photographed images, undesirable portion may be extracted as a noise in image data or the corresponding portion of an object may be missing, which has been other problem with the above conventional method according to the prior art.
Other example of the conventional image processing technologies is the one disclosed in the Japanese Patent Publication (Kokai) No. Heisei 7-154777 "An Image Processor and A Video Telephone Device". In the above publication, proposed is a device wherein infrared light is radiated on an object from the light receiving means side, and the input light is separated into visible light and infrared light reflected by the object by that light receiving means, and an area where the strength of infrared light is larger than a threshold value is extracted from visible light image as a mask area, and thereby only an image of an object at a short distance from a camera may be easily extracted. The object extracting method described in the above publication is one that radiates infrared light to an object, and separates reflected visible light and reflected infrared light from the light in the received light scope, and extracts a portion where the strength of infrared light exceeds threshold value among images created by separated reflected visible light as an object.
However, the technology in the above Japanese Patent Publication (Kokai) No. Heisei 7-154777 may require radiation of strong infrared light onto an object according to illumination condition or other conditions. And the use of an infrared light radiating device that can radiate strong level of infrared light increases costs to a great extent, which has been a problem with the above conventional method according to the prior art.
And in the case when an object is a human being, the document "Effects and Safety of Ultraviolet and Infrared Light on Eye" (The Illustration Society Magazine, vol.61, No.11, Pages 636 to 641, 1977) reports there was a fear that the human body was affected badly if a high level of infrared light is radiated onto a human body.
A further example of the conventional image processing technologies according to the prior art is the one disclosed in the Japanese Patent Publication (Kokai) No. Heisei 7-220095 "An Object Image Extracting Device". In the above publication, proposed is a device wherein data about an object and data about an image pickup device sensor are accumulated in memory in advance, and when an object is extracted from an image obtained by using image pickup device, a precise object in an image is extracted without noise by using the data accumulated in memory. The object extracting method described in the above publication records the data about an object such as its size and so forth, and the data about the distance between the principal point of the object, the focal length and the size of sensor, the number of pixels, and other data about image pickup device in advance, and it forecasts an object existing portion in an image on the basis of the data about image pickup device, and extracts part of a photographed image to become a candidate for object. And the most consistent part with the data about the object in the part is selected as an object.
However, the technology described in the above Japanese Patent Publication (Kokai) No. Heisei 7-220095 requires the acquisition and accumulation in advance of the data about object and the data about image pickup device, and it was impossible to extract an image of an object whose data were not stored in advance, which has been a problem with the above conventional method according to the prior art.
Furthermore, the extraction of an object according to the above prior art requires the distance from the principal point of an image of an object to the object concerned, or the distance from the principal point of an image of an object to the image. And to obtain the distance from the principal point of an object to the object concerned, required was an expensive device such as an infrared light radiating device and so forth. And it was difficult to obtain a stable distance from the principal point of an image to the image.